High temperature chromium-nickel alloy

ABSTRACT

An alloy containing 45 to 55 percent chromium, 45 to 55 percent nickel, 0.003 to 0.4 percent cerium, up to 1.5 percent titanium, up to 1.5 percent zirconium, and up to 1.5 percent hafnium. The titanium, zirconium and hafnium may be present separately in amounts up to 1.5 percent or they may be present in combination in an amount up to 3.0 percent.

States Mueller et al.

[ Jan. 22, W74

[ HIGH TEMPERATURE CHROMIUM-NICKEL ALLOY [75] Inventors: Charles P. Mueller; Gunes M. Ecer,

both of Pittsburgh, Pa.

[73] Assignee: Cyclops Corporation, Pittsburgh, Pa.

[22] Filed: Nov. 18, 1970 [21] Appl. No.: 90,847

[52] US. Cl. 75/134 F, 75/171, 75/176 [51] Int. Cl. C22c 19/00, C22c 29/00 [58] Field of Search 75/134 F, 134 R, 171, 170,

[56] References Cited UNITED STATES PATENTS 3,627,511 12/1971 Taylor et al. 75/171 X 2,067,569 1/1937 Hessenbruch 75/171 2,219,445 10/1940 Franks 75/171 2,809,139 10/1957 Bloom 75/171 X 3,607,245 9/1971 Gottlieb 75/171 X Primary Examinerl-lyland Bizot Assistant Examiner-.l. E. Legru Attorney, Agent, or Firm-Webb, Burden, Robinson & Webb [5 7 ABSTRACT 2 Claims, No Drawings 3,787,202 i a a E C ill r LOY metal substrate.

The benefits achieved by the addition of cerium are obtained in a chromium-nickel alloy having at least 45 percent chromium and at least 45 percent nickel. The presence of titanium, zirconium and hafnium either alone or in combination in the alloy is not detrimental since these reactive elements are present in the chromium-nickel matrix without having any appreciable effect on the high temperature corrosion resistance of the alloy.

However, since titanium, zirconium and hafnium are 'strong nitrogen forming elements, their presence in the alloy prevents the alloy from including excessive HIGH TEE This invention relates to a high temperature corrosion resistantalloy having a composition within the ranges set forth hereinafter. The term corrosion as 5 used herein means the gradual deterioration or breakdown of the alloy by dissolution, oxidation or other means attributable to a chemical process.

High temperature corrosion resistant alloys produce a protective surface coating during service. Stainless steels are examples of alloys which form selfmanufactured protective surface oxide scales at high temperatures. While the presence of certain elements in a prrt tecttvetoxidzfzcaclle(isbknglwn t; increase the amounts of nitrogen in solid solution. The amount of gree 0 P ec or e y e Sc g It necessary titanium and/or zirconium and/or hafnium required deto consider other factors when determining the compopends upon the amount of nitrogen present in the alloy P? of a alloy temperature applications during the final stages of melting, but it has been deterquiring corrosion inhibition. Some of these factors are mined that 03 percent is the effective minimum if the strength of the scale formed on the substrate, the these metals are used degree of adherence of the scale to the substrate and The broad composition range of our hove] alloy is as the growth stresses in the scale. All of these properties f ll are important in determining the composition of an alloy to be used at high temperatures in corrosion resis- Element Percent y Weight tant applications.

- Chromium 45 55 An alloy having a composition within the ranges of Nickel 45 55 our invention has good corrosion resistance at temper- 2 2; atures up to about 2250F and has numerous applica- Zirconium Us to 1:5 tions in the chemical and petroleum industries where Hafmum UP to r T 1 l fT'ta high temperatures are encountered under extremely fif i 'lh corrosive conditions for long periods of time. Addition- P Hflfnium UP 10 3 ally, alloys within our composition range can be heat M treated and worked to produce shapes for fabricating It h ld b d t d th h th d f producing stfucml'esthe alloy and the processing to which the alloy is to be Our invention consists in an alloy which is more resissubjected must be considered in determining the spetant to corrosion at high temperature than presently cific amount of cerium which is added.

known alloys. The reason that our alloy is resistant to The following non-limiting examples show the advancorrosion at high temperatures is believed to be betages of alloys within the range of our invention. The

cause the surface oxide layer is highly resistant to spallchemical analyses of the various heats of the examples ing and, hence, is more adherent to the substrate than are set forth in Table I. In each instance cerium was the oxides formed on the surfaces of known high temadded after the chromium-nickel alloy was melted and ...P 91.12? dxa es qaarwiesn fl PEFlz.

TABLE I ANALYSIS PERCENT BY WEIGHT I Heat Number Cr Ni Ce C Mg S P Ti Fe O of b nickel, and iron.

alloy are believed to result from the addition of cerium A consideration of the analyses of the various heats to the chromium-nickel matrix. 4 shows that the amount of cerium in the alloy progres- The addition of small amounts of cerium to a chromisively lowers the oxygen content of the alloy. The alloys um-nickel alloy decreases the oxidation rate of the containing the lower amounts of cerium showed good alloy by a substantial amount, and, thus, the alloy is hot workability, but ingots containing over 0.12 perbetter able to resist corrosion at high temperatures. cent cerium were not workable even though the oxygen -NlI(I]l(ElL increases the adhesion of the outer oxide scale to the Analysis of outer oxide scale formed on alloys in accorcontent was lower than in the ingots containing the dance with our invention shows that the scale is subsmaller amounts of cerium.

stantially completely Cr O which indicates that the ce- In order to show the effect of cerium on oxidation rerium does not diffuse into the outer scale. It is believed sistance, a number of tests were conducted to deterthat the cerium forms a thin, non-uniform, discontinu- 5mine the weight change and oxide scale adherence ous oxide layer between the outer oxide scale and the characteristics of our alloy including various amounts metal substrate. Thus, an additional barrier to diffusion of cerium. A series of oxidation tests were conducted. of oxygen and chromium is produced on the metal sur-' for various time periods at 1,800F and 2,000IF with face. By forming an intermediate oxide layer, the cetemperature cycling. The results of these tests are rium has a substantial effect upon oxide spallation and Shown in Tables L and 3 .7 4 TABLE II OXIDATION WEIGHT CHANGE AT 1800F Weight Change" Cerium (mg/cm) Sample Condition 45 Hours 108 Hours 205 Hours Condition of Oxide Scale Heat 1 Wrought 0.0 0.0 5.50 6.51 All Spalled Heat 3 Wrought 0.008 +0.21 +0.34 +0.22 Partially Spalled Heat 4A As-Cast 0.12 +0.59 +0.80 +1.07 Adherent Heat 48 As-Cast 0.12 +0.59 +0.89 +1.10 Adherent Heat 5A As-Cast 0.28 +0.73 +0.99 +1.27 Adherent Heat 5B As-Cast 0.28 +0.77 +0.99 +1.29 Adherent Heat 6A As-Cast 0.38 +0.66 +0.92 +1.25 Adherent Heat 68 As-Cast 0.38 +0.65 +0.95 +1.26 Adherent l) Specimen size: .25" .75"Xl.5". I I I (3) Weights measured at room temperature in as-cooled conditions. (2) Oxidation test carried out in box furnace with specimens quartz containers. "Three cyclcs f 63 and 97 TABLE III OXIDATION WEIGHT CHANGE AFTER 63 HOURS AT 2000F Cerium Weight Change Sample Condition (mg/cm) Condition of Oxide Scale Heat 1 Wrought 0.0 6.9 All Spalled Heat 2 As-Cast 0.003 --8.2 All Spalled Heat 3 As-Cast 0.008 4.3 Partially Spalled Heat 4 As-Cast 0.12 +1.5 Adherent Heat 6 As-Cast 0.38 +1.4 Adherent (1) Specimen size: .25"X.75" 1.5". (3) Weights measured at room temperature. (2) oxidizing media: Air in furnace. i 7 V I I TABLE IV OXIDATION WEIGHT CHANGE AFTER 430 HOURS AT 2000F Cerium Weight Change Condition of Sample Condition (mg/cm) Oxide Scale Heat 1 Wrought 0.0 16.22 All Spalled Heat 2 As-Cast 0.003 3.71 Partially Spalled Heat 2 Wrought 0.003 5.63 Partially Spalled Heat As-Cast 0.28 +1 1.93 Adherent Heat 6 As-Cast 0.38 +5.00 Adherent l) Specimen size: Approximately 0.3"XO.750"X1.00". (3) Weights measured at room temperature.

(2) Oxidation test carriedgutin bqx furnace.

The tabulations in the above tables show that inshowed partial spalling in small platelets, and the samcreased amounts of cerium promote adherence of the 40 ples with larger amounts of cerium showed no spalling oxide scale to the substrate. Thus, scale formed on at all. specimens with no cerium spalled off in large platelets, The reuslts of continuous weight gain measurements while the samples containing small amounts of cerium due to oxidation are set forth in Tables V through IX.

TABLE V TABLE VI CONTINUOUS WEIGHT GAIN FOR OXIDATION AT I750F 3"" commuous WEIGHT GAIN FOR OXIDATION AT (mg/cm 2000F, 0% CERlUM (HEAT 1 Weight Gain Time 0% Cerium 0.008% Cerium 0.28% Cerium Time (Hours) (mg/cm) (Hours) (Heat 1) (Heat 3) (Heat 5) 0.1 0.32 0.1 0 0.011 -0.023 05 0.2 0.020 0.031 -0.012 0.3 0.111 0.053 0.4 0.162 0.077 g: 0.5 0.110 0.046 0.75 0.187 0.093 1 1 1.0 0.243 0.220 0.139 65,7 gm l.5 0.265 0.197 74.5 8.39 2.0 0.297 90.5 9.04 2.5 0.394 0.330 0.232 98.5 9.37 3.0 0.425 0.352 0.294 e .3..- ..W..... 2. W. .eu e e. re e 3 '(l) Specimen size: 2.046"X0.36l" 0.09l". 1) Total surface area of specimens: Approximately 9.5 cm. Specimen condition: A5473"- (2) Specimen m Aswan (3) Dry air flow: 5.25 liters per minute; Dew point: 100F.

(3) Dry air flow: 5.25 liters per minute, Dew point: 100F. (4) weigh measured 2000": during mating (4) Weights measured at 1750F during testing. V n V 1 TABLE VII CONTINUOUS WEIGHT GAIN FOR OXIDATION AT 2000F, 0.03% CERIUM (HEAT 2) TABLE IX-Continued Weight Gain Weight Gain Time (Hours) (mg/cm) 5 Time (Hours) (mg/cm) 7l.l 2.19 3213 i333 100.8 2.31 21 1.68

'(l) Specimen size: 2.l08"X0.3l3"X0r085". v I i 7 92-9 6-97 (2) Specimen condition: Ascast. 99.9 7.21 (3) Dry air flow: 5.25 liters per minute; Dew point; I00F.

(4) Weights measured at 2000F during testing. '(I) Specimen size: l.7l8"X0.27l"X0.l0l". I (2) p m ondition: As-Cast. The results of the tests at 1,750F are not as accurate 2:; tfgzggi 'm f zjf 'g as those at 2,000F due to smaller changes in weight, but this series of tests shows the general trend in the TABLE VIII change of weight due to oxidation as more cerium is included in the alloy. The tests at 2,000JF (Tables VI CONTINUOUS WEIGHT GAIN FOR OXIDATION AT IX) clearly show the beneficial effect of cerium in re- ZOOOOF 000% CERIUM wg e 2O tarding the rate of oxidation. The samples containing Time (Hours) ori /cm) cerium form progressively thinner and more adherent OJ 0-31 scaleas the cerium content was increased. Based upon the test results shown in Tables II IX, :13 133 it may be concluded that cerium increases the adherence of the oxide scale to the metal substrate and deiiii 5:33 ,qrs s sths thickness of the l 7.. 23:; iii}, The alloy of our invention may be used for a number 6 -2 5- of different applications such as, for example, metal 33:; if fired heaters, reactor vessels for treating pulping li- 99.3 5.60 quors, refinery heaters, acid handling equipment and e metallurgical heat treating furnace components. I) Specimen size: 2.l07"X0.377"X0.|00". e condiliow While we have described a preferred embodiment of :2; 3231x33111,111,535 321;fljfi 'gf 00F our invention, it may otherwise embodied within the Y I A V A A m M m .999? 9gb? P pdi m V. W TABLE IX 1. A high temperature corrosion resistant alloy conh WEIGHT GAIN FOR OXIDATION AT sisting essentially of 45 55 percent chromium, 45 55 200005 028%CER1UM (HEAT 5) 40 percent nickel, 0.003 0.4 percent cerium and beweishl Gain tween 0.3 percent and 3.0 percent of at least one of the Time (mg/cm) metals selected from the group consisting of titanium, OJ 020 zirconium and hafnium, there being no more than 1.5 3% 8-3 percent of anyone of said metals. 1 1) V i A W 57 J" 2. A high temperature corrosion resistant alloy con- 3'3 13; sisting essentially of 45 55 percent chromium, 45 55 8:0 1.34 percent nickel, 0.003 0.4 percent cerium and be- 33 1-3? We?!) 1132 m. and P n tan um, 7, 0,4713 2:14 7 a r H ,v. 

2. A high temperature corrosion resistant alloy consisting essentially of 45 - 55 percent chromium, 45 - 55 percent nickel, 0.003 - 0.4 percent cerium and between 0.3 percent and 1.5 percent titanium. 